Western Blotting

Background

The Ras family small GTPase Ran is involved in nuclear envelope formation, assembly of the mitotic spindle, and nuclear transport (1,2). TPX2, a target of active Ran (RanGTP), is a microtubule nucleating protein. TPX2 is inactive when bound to nuclear importin-alpha. RanGTP activity disrupts this interaction, relieving inhibition of TPX2 (3). TPX2 binding activates Aurora A kinase and promotes its localization to the mitotic spindle (4,5). DNA damage in mitosis leads to loss of interaction between Aurora A and TPX2 and inactivation of Aurora A kinase (6). TPX2 is highly expressed in pancreatic cancer cells, and knockdown of TPX2 expression in these cells is associated with increased sensitivity to paclitaxel (7).核膜形成，有丝分裂纺锤体的聚集以及核转运过程都涉及了Ras家族小GTPase Ran蛋白（1.2）。TPX2，活化Ran（RanGTP）的一个靶蛋白是一个微管核形成蛋白。TPX2与细胞核输入-alpha结合时是失活状态。RanGTP的活性能够破坏这种结合，减弱TPX2的抑制作用（3）。TPX2的结合会激活Aurora A激酶促进其定位到有丝分裂的纺锤体（4,5）。有丝分裂时DNA损伤会丢失Aurora A和TPX2的结合从而使Aurora 激酶失活（6）。TPX2在胰腺癌细胞中高表达，敲除TPX2会增强细胞对紫杉醇的敏感性（7）。